CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 5.9	$ 4.5
Preferred Stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred Stock, shares authorized	100,000	100,000
Common Stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common Stock, shares authorized	240,000,000	240,000,000
Common Stock, shares issued	85,768,120	85,214,345
Common Stock, shares outstanding	85,768,120	85,214,345
Non-voting Common Stock
Common Stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common Stock, shares authorized	7,125,000	7,125,000
Common Stock, shares issued	0	0
Common Stock, shares outstanding	0	0
Class C Common Stock
Common Stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common Stock, shares authorized	20,000,000	20,000,000
Common Stock, shares issued	0	0
Common Stock, shares outstanding	0	0